Difference between Search Engine and Directory

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Search Engines
Search engines use computer programs called Robots to automatically go from page to page through the web, reading content, and adding it to their databases. To speed up the process of getting your site indexed, they usually have a way for you to submit your site for indexing. You usually only have to tell a Search Engine the URL (address) of your site and it takes care of the rest.

Directories
Directories are run by humans who review web sites and categorize them within their directories. This leads to a more abridged set of sites which can good or bad depending on what you're searching for.

A directory is eventually a website which looks just like search engine but is organized as a series of sections under which appropriate sites are filed. The content of a directory is vetted by human editors before becoming a part of the directory.

A web search engine is designed to search for information on the World Wide Web and FTP servers.

Main difference between search engine and directory lay is the way websites get entered into their index. People submit their sites to the directories, which are reviewed by human editors. Think of the directories as collections of Internet sites organized by subject. Search engines work by sending out a spider to fetch as many documents as possible. Following, another program called an indexer, reads these documents and creates an index based on the words contained in each document.